posthumous name (shi) of an emperor (reigned AD 75–88) of the Han dynasty (206 BC–AD 220), whose reign marked the beginning of the dissipation of Han rule.

The Zhangdi emperor's reign was the third since the Liu family had restored the Han imperial dynasty following Wang Mang's usurpation of power, and historians generally refer to the period as the Dong (Eastern) Han (AD 25–220). In many ways, Zhangdi's reign seemed to bring the Dong Han to new heights; the famous general Ban Chao continued his conquests of Central Asia, while internally Zhangdi followed a mild, peaceful policy. Nevertheless, eunuchs increased their power at court, and the great landed families grew more powerful in the countryside. Scheming officials and eunuchs completely dominated the country after Zhangdi's death, and, of the nine rulers who ascended the throne during the century following his demise, the oldest was 14.